The present invention relates to an apparatus for cutting an edge portion or a selvage rubber portion of a coating sheet wherein a plurality of cords arranged at substantially equal intervals and in parallel with each other and conveyed along a predetermined path are integrally coated with rubber or the like in such a manner that the cord portions are expanded, to a predetermined length from the most externally positioned cord portion of the coating sheet in transversal direction thereof.
The coating sheet wherein the cord portions are expanded includes, for example, rubber coating sheets embedding reinforcing cords therein, which are used for production of a tire and the like. The coating sheet is produced by coating a tire cord fabric in which a plurality of cords 1-1, 1-2, . . ., 1-n are arranged at substantially equal intervals and in parallel with each other as shown in FIG. 1 with rubber 3 by feeding the tire cord fabric into a calender having rolls 2-1, 2-2, 2-3 and 2-4 as shown in FIG. 2 in the longitudinal direction shown by an arrow A. FIG. 3 shows a cross-sectional view of the thus produced coating sheet 4 and the coated portions (cord portions) 5-1, 5-2, . . ., 5-n where the cords 1-1, 1-2, . . ., 1-n are coated with rubber, are expanded, that is, the thickness (diameter) of the coated portions (cord portions) is larger than that of flat portions 6 which connect the cords with each other, and the coating sheet has selvage rubber portions 7 which extend outwardly from the most externally positioned cord portions 5-1 and 5-n respectively in uneven width. The coating sheet 4 is cut at a given angle and in a given width and the thus cut coating sheets are press-bonded and connected at the selvage rubber portions 7 in such a manner that the cords are placed at a given angle to the longitudinal direction, thereby forming a long cord inclined or bias fabric. In the thus formed cord inclined fabric, it is the necessary conditions for producing the tires which are high in the drive feeling and are strong and safe, that the distance between the cords is constant. To this end, it is necessary to precisely cut out the width of the selvage rubber portions 7 to be press-bonded and connected, to the given width.
In one conventional means, use is made of a cord position detecting device including a magnetic sensor as described in, for example, Japanese Utility Model Laid-open No. 26,234/81, the position of the most externally positioned cord is detected, and a cutter is placed at a predetermined position to the detected cord position, thereby cutting out the selvage rubber portions to the given width. In another conventional technique, use is made of an apparatus for measuring width of the selvage rubber portion including a light receiving element array as described in Japanese Patent Laid-open No. 125,805/82, the width of selvage rubber portion is optically measured and a cutter is placed at a predetermined position to the most externally positioned cord portion based on the detected salvage rubber portion, thereby cutting out the selvage rubber portion to the given width. In the former cutting device, however, the position of the cord is detected by the magnetic sensor so that the cutting device can be applied to only the cord consisting of steel and cannot be applied to the cord consisting of organic fibers, such as nylon and thus this cutting device cannot be utilized for various purposes. In the latter cutting device, on the contrary, width of the selvage rubber portion is optically measured so that the cutting device can be effectively applied to whether the cord consists of steel or of textile. This device, however, comprises a light source for illuminating the coating sheet and a light receiving element array for receiving reflected light from the coating sheet which are directly arranged near the coating sheet, in order to measure width of the selvage rubber portion so that the measuring device becomes large. The measuring device and the cutter, therefore, cannot be arranged integrally so that the distance between them becomes great in the conveying direction of the coating sheet. This causes a time lag so that the selvage rubber portion cannot be cut out to a given width. It is desirable to develop an apparatus capable of cutting the selvage rubber portion of the coating sheet to the given width with high precision, regardless of kind of cords such as steel cord or textile cord.